If sludge such as muds, viscous liquid materials, shells or the like is attached on the inner walls of the pipes of heat changers used in the petrochemical plants and power generating plants, they degrade efficiency of the heat exchangers and cause corrosion of the pipes to leak fluid from the pipes. Thus, it is necessary to periodically eliminate the sludge attached on the inner walls of the pipes in order to maintain the efficiency and lifetime of the heat exchangers.
Conventionally, the sludge on the inner surfaces of various fluid pipes is eliminated by scrubbing and cleaning the inner surfaces of the pipes with metal brush fixed at an end of a long stick or by rapidly flushing cleansing water containing chemicals or some high pressure water into pipes so that high pressure is applied onto the inner surfaces of the pipes with or without the use of any contaminant-eliminating apparatus.
However, in using metal brush, it is impossible to clean the inner surfaces of pipes long beyond the reach of the bar of the brush. When using only by rapidly flushing cleansing water containing chemicals or some high pressure water into pipes. The sludge which are hard fastened onto the inner surfaces of the pipes for a long time is likely to be left. In particular, the chemicals contained in the cleansing waters, it is important to remove the chemicals completely without any remaining after the cleaning of the sludge.
FIGS. 8, 9 and 10 show three conventional apparatuses for eliminating sludge on the inner surfaces of pipes.
The conventional sludge eliminating apparatus 30 shown in FIG. 8 is disclosed in Japanese Utility Model Publication sho 40-33657 (Nov. 25, 1965). The conventional sludge eliminating apparatus 30 consists of several bowl-shaped pressing plates 36 having on its bottom surface a plurality of passing holes 34 with respective control valves 33 on a screwed rod 32, a cap 31 of a truncated cone type placed at one end of the rod 32, and an extractor 38 having a plurality of elastic pieces petal-likely extended between the cap 31 and the plate 36, and in-between the plates 36.
Since the apparatus 30 has a complicated structure which can adjust the pressure of water applied onto the plates 36 by the operation of the control valves 33 attached to the plurality of passing holes 34 of the plates 36, large sized sludge can not be properly discharged. Further, since the space between elastic pieces of the extractor 38 is very narrow, the cleansing water passing through the passing holes 34 does not swirl but flow straightly in the pipes. Therefore, the sludge scratched off by the elastic pieces 37 and sludge incompletely scratched off and still remaining on the inner surfaces of the pipes can not be sufficiently taken along with the cleansing water out of the pipes.
The apparatus 40 shown in FIG. 9 is disclosed in Japanese laid-open Utility Model Publication sho 49-98062. The apparatus 40 comprises a cleaner member 43 having a circular plate portion 41 and a rib portion 42 taperingly protruding in the backward direction of the peripheral surface of the circular plate portion 41. A coupling hole 44 is formed at the front center of the circular plate portion 41 of the cleaner member 43 and a coupling protrusion 45 which can be coupled in the coupling hole 44 is formed at the back center of the circular plate portion 41 so that the cleaner members 43 can be connected in series according to the cleaning capacity of the apparatus 40.
In the apparatus 40, the rib portion 42 of the cleaner member 43 is closely contacted onto the inner surfaces of pipes by the pressure of water and then the cleaner member 43 is moved in the pipes, so that the sludge in the pipes can be scratched off. However, since the cleansing water can not smoothly flow in the moving direction of the cleaner member 43, the sludge being removed can not be rapidly discharged out along the cleaning water. Also, if large amount of the removed sludge is accumulated at the front of the cleaner member 43, the cleaner member 43 can hardly move forward due to the resistance of the accumulated sludge consequently the scratching force less applies to the sludge.
The apparatus 50 shown in FIG. 10 is disclosed in Korean Utility Model Application No. 18162 filed on Jul. 20, 1994 by the same applicant of this application and published. The apparatus 50 consists of several metal cylinders 51 provided with protrusive eliminating teeth 51A, a spacer 52 between the metal cylinders 51 in a truncated cone shape so that cleansing water flowing through the spacer 52 extends, a fixing pin 54 inserted into both the metal cylinder 51 and the spacer 52 to fix them at a certain position and a water pressure plate 53 having several concentric elastic pieces 53A of different diameters and several notches 53B for receiving higher water pressure. In the apparatus 50, the outflowing inserting grooves 51B formed in each of the metal cylinders 51 are arranged not to be placed in a straight row for passing cleansing water to swirl.
The apparatus 50 shown in FIG. 10 has higher efficiency in scratching off sludge attached in the pipes than the apparatuses 30 and 40 shown in FIG. 7 and 8 respectively having advantage that it moves smoothly in the pipes by receiving higher water pressure due to the water pressure plate 53 having several elastic pieces 53A with the inserting grooves 53B. However, in the apparatus 50, it is only the protrusive elimination teeth 51A that work for removing the sludge in the pipes. Therefore, if the teeth 51A fails to completely scratch off all sludge, some sludge is likely to remain in the pipe. Further, the apparatus 50 has not enough flexibility to be used for U-shaped pipes. Also, there is another problem that the apparatus 50 cannot be manually placed in a pipe of an heat exchanger when the heat exchanger's structure does not allow that.